Recently, a sensor-equipped display device comprising a sensor (often called a touch panel) capable of detecting contact or approach of an object, has been put into practical use. As an example of the sensor, a capacitive sensor capable of detecting contact or approach of an object, based on a variation in electrostatic capacitance is well known. A detection electrode and a sensor driving electrode constituting the sensor are disposed in a display area in which images are displayed, and opposed to each other with a dielectric interposed between the electrodes. The detection electrode is electrically connected to a lead line located outside the display area.
Requests for downsizing of the display device are increased while the display area is extended, and a periphery outside the display area tends to become a narrow frame. For this reason, the sensor driving electrode and the lead line are often disposed closely to each other. In this case, the lead line may function as a sensor due to capacitive coupling between the sensor driving electrode and the lead line. For example, if an object which is to be detected contacts or approaches the vicinity of an outermost periphery of the display area, variation in the electrostatic capacitance of the lead line is detected. For this reason, the detection electrode connected to the lead line performs error detection as if the detection electrode detected the detected object at a position different from a position where the detection electrode should detect the detected object.
Thus, for example, a technology of disposing a grounded conductive material outside the display area between the sensor driving electrode and the outer peripheral line (lead line) and blocking the capacitive coupling between the sensor driving electrode and the outer peripheral line has been proposed.